"These are true brain conditions," Mordecai said, "and we have to get away from the blaming."

In reality, he explained, mental health disorders are rooted in factors like genetics, traumatic experiences and imbalances in brain chemicals.

Dr. Jeffrey Borenstein, a psychiatrist who was not involved in the survey, agreed.

"Psychiatric conditions are not moral weaknesses or character flaws," said Borenstein, president of the New York City-based Brain & Behavior Research Foundation.

Borenstein said he was surprised by how many survey respondents mistakenly believed that character was involved. Over 60 percent thought that personal weaknesses were at least partly responsible for depression, for example.

"We clearly have a long way to go in educating the public," Borenstein said. "These conditions are equal to any other medical condition. In this case, the organ affected is the brain."

The poll, conducted online in August, included a nationally representative sample of just over 3,000 U.S. adults.

When asked about the national climate around mental health, 70 percent said they thought Americans were now more open to discussing it.

People also appeared willing to talk about their own struggles. Nearly 40 percent said they'd faced a mental health "issue" at some point, and nearly all of those people -- 92 percent -- had sought some kind of help.

In another positive finding, 70 percent of respondents said they would be comfortable offering support if someone they knew had a mental health condition.

But the poll also uncovered inconsistencies.

Three-quarters of respondents felt at least somewhat informed about mental health conditions, while a similar percentage said the disorders should be treated no differently from physical health problems.

Yet they also thought personal character was a factor in many mental health conditions. Fully 80 percent thought that was true of people with alcohol or drug addiction.

And a significant number thought "most people" with mental health disorders can get better on their own. That included one-quarter of millennials, Mordecai pointed out -- which is concerning.

"You wouldn't walk around with a broken leg, thinking, 'I'll just heal this myself,'" he said.

In another concerning finding, more than half of respondents said they thought a family member or friend was silently struggling with a mental health condition -- out of "fear of stigma" or shame.

In those cases, Borenstein said, people can try to be proactive -- telling their friend that they are concerned and ready to offer help if it's wanted, for example.

Mordecai pointed to one of the bright spots in the survey: "If you're dealing with a mental health issue, these results show that there are people around you who stand willing to help," he said.

Recognizing when you have symptoms, and speaking up about it, are the first steps toward treatment and recovery, Mordecai said.

"We have effective treatments," he stressed -- from "talk therapy" to medications.

Borenstein agreed. "These are conditions that no one should be ashamed of," he said. "It's very important that people seek help, or encourage others to seek help when they need it."